1. Field of the Invention
The present invention relates generally to optical fiber, and particularly to low and medium dispersion optical fibers suitable for dense wavelength division multiplexing.
2. Technical Background
Optical fibers such as medium dispersion fibers (MDF) with dispersion between about 6 to 12 ps/nm/km at a wavelength of 1550 nm are suitable for dense wavelength division multiplexing (DWDM). These dispersion fibers (MDFs) typically have a central core 10, with a central inner core region 11, a positive refractive index annular ring 12. The core sometimes includes at least one depressed index region 14 adjacent to the ring. The core is a fiber region containing at least 90% of signal light. These MDFs provide 6 to 12 ps/nm/km but can have an effective area of no more than 60 μm2, and are relatively expensive to manufacture due to tight tolerance and core design complexity.
Optical fibers such as medium dispersion fibers (MDF) utilized in so-called “dense wavelength division multiplexing conditions” can be subjected to a variety of bending environments, in a manner which induces bend losses in optical signals transmitted through the optical fiber. Some applications that can impose physical demands, such as tight bend radii, compression of optical fiber, etc., that induce bend losses include the deployment of optical fiber in optical underground cable assemblies, buckling induced by large temperature variations, and small bend radius multiports located in cabinets that connect feeder and distribution cables.